Power-operated sliding door gear



Sheet of2` H.A JQsTRE'l-'TON POWER-OPERATED SLIJING yDOOR GEAR April2z,` 1969 Filed March 17, 1967 H. J. sTRETToN 3,439,454 POWER-OPERATEDSLIDING DOOR GEAR snm Apfil 22, 1969 Filed March 17, 19e?l United StatesPatent() U.S. Cl. 49-362 3 Claims ABSTRACT OF THE DISCLOSURE Apower-operated sliding door gear which incorporates a lead screw andtravelling nut, a spring-loaded tr1gger pivoted on the nut, two pawlspivoted on a carriage connected to a door, and an electromagnet forholdmg the pawls in a position in which they can be engaged by thetrigger. If power fails the pawls dropI clear of the trigger and thedoor can be manually opened; 1f the door sticks the trigger overridesthe pawls.

It has long been the practice to fit swinging doors to the entrance ofpublic buildings and in many communlties it is a statutory regulationthat the doors should swing outwards. This feature facilitates the rapidexit of the occupants of a building in the event of a fire or other suchdisaster which may give rise to panic.

The introduction of power operated sliding doors has been made diicultby such statutory conditions. A power operated sliding door isnecessarily rigidly supported at its top and bottom edge so that itshall constitute a secure burglar-proof closure when a building isunoccupied. If the door is motivated by an apparatus depending on thesupply of electricity, it is very possible that cond1- tions which couldgive rise to panic among the occupants of the building could alsodisrupt the supply of electricity to the door. Any mechanism used todrive the door leaves to one or other side or both of the opening shouldtherefore become automatically disconnected from the door leavesthemselves in the event of a power failure, to enable the door leaf orleaves to be manually slid to one side easily and permit the exit of theoccupants. Even under far less severe conditions of damage such as apower failure or supply fault such a facility would enable the doors tobe used manually until an effective supply was restored. Means alreadyexist whereby the door leaf can be carried in a sliding `sub-frame Vandcan be hinged at its outer edge in the manner of a swing door but thismethod of overcoming the problems of power failure and panic iscomplicated and adversely affects the finished appearance of the wholeinstallation.

According tto the invention there is provided a poweroperated slidingdoor gear including a driving mechanism for transmitting :a drivingforce to at least one door leaf, which mechanism includes apower-operated coupling device arranged and adapted to transmit thedriving force only when door-operating power is present. Thus the devicewill, in the event of a failure in the power supply, automaticallydisengage so that the door is free to be moved manually. According to afurther feature of the invention the device which will disengage itsdriving and driven parts in the event of resistance to movement due toan obstruction interfering with any part of the driven portion of themechanism or the door leaf or leaves. According to a further feature ofthe invention the device will automatically re-engage the driving anddriven parts when the power supply is restored or the obstructionremoved.

According to a preferred embodiment of the invention the device itselfserves to transmit thrust and includes two pawls carried by one of theparts, the pawls having a normal rest position and a second position inwhich they are held electromagnetically when the doorgoperating powersupply is on and in which they can be engaged by a pre-determinedlyspring-loaded trigger member carried by the other of the parts. Thepawls face each other with a space between just big enough to receivethe trigger. Thus, normally, when the power is on, door-opening andclosing forces are transmitted from trigger to pawl (or vice versa). Ifthe power fails the pawls return to their rst position and the drivingconnection between the driving and driven parts of the mechanism isbroken so that the door or ydoors can be moved by hand. To break thedriving connection if, when the power is on, a moving door meets anobstruction, the trigger can pivot against the spring restoring force toride over the operative pawl. In either case the driving connection isrestored when normal operation is resumed, by return of the pawls totheir second position and/or the trigger riding over the pawls into thesaid space.

The preferred embodiment of the invention Will be further described withreference to the accompanying drawings, in which:

.FIGURE 1 is a front view of a door operating mechamsm incorporating theinvention;

FIGURE 2 is a rear view of part of the mechanism, on an enlarged scale,showing the device for breaking the driving connection;

FIGURE 3 is a plan view of the part shown in FIG- URE 2;

FIGURE 4 is a cross-section on line IV-IV of FIG- URE l, on the samescale as FIGURES 2 and 3;

FIGURE 5 is a sectional view, on line V--V of FIG- URE 2, of a detail ofthe device; FIGURE 6 showing the same detail in end view;

FIGURE 7 is a view, partly in section, in the direction of arrow VII inFIGURE 2, of a further detail; and

FIGURE 8 is a cross-section on line VIII-VIII of FIGURE 7.

FIGURE 1 shows a box section beam 1 (one wall being omitted to show thecontents) in which is a door operating mechanism including an electricmotor 2 driving a lead screw 3 on which is a nut 4 prevented fromrotating by a guide 5. Thus operation of motor 2 moves nut 4 along screw3.

FIGURE 1 also shows bi-parting door leaves 8 and 13, suspended bybrackets 9, 14 and 24 from balls 25 running in a track 26 in beam 1(FIGURE 4). Bracket 9 carries leaf 8 and is clamped to a wire rope 10which passes around idler pulleys 11, 12 and is joined at its ends to abracket 14, which carries leaf 13, by means of a compression spring 27and a screw 28 serving to set and maintain the tension of the rope, Thusleaf 13 will move in sympathy with but in the opposite direction to leaf8.

Nut 4 forms the driving part of a dis-connectable coupling device and isconnected, in operation, to leaf 8 by a device indicated generally at 7in FIGURE 1 and shown in more detail in FIGURES 2 to 8. The maincomponents of the device 7 are two opposed pawls 17, 18 pivoted on abracket 29 which also carries coils 21, 22. A hanging trigger 6 ispivoted on nut 4 and a double-acting springloaded plunger unit 15 ismounted on nut 4 and serves to hold trigger 6 in a vertical position.Bracket 29 is connected to bracket 9, but could be connected to leaf 8directly.

The natural tendency of pawls 17, 18 is to adopt a first position asshown by broken lines 171, 181 under the action of their own weight; inthis position they are clear of trigger 6. Coils 21, 22 are connected tothe motor power supply by a trailing lead 30 and are energized, when thepower is on, so as to hold the pawls in the second position, shown infull lines, in which the pawls and trigger will touch on axial movementof either.

In normal operation, therefore, coils 21, 22 hold pawls 17, 18 up, andtrigger 6 lies between the pawls as shown. When nut 4 is moved by screw3, trigger 6 engages one or the other pawl to move leaf 8 and hence leaf13, with pivoting of trigger 6 being prevented by unit 15.

If the power fails the pawls will drop to rest against non-magnetic pins19, 20 on bracket 29. The door leaves are then disconnected from nut 4and can be moved by hand.

If the circumstance arises whereby the mechanism of the door is inoperation but an obstruction prevents the door leaves from moving orstops them from completing their movement, then the trigger 6 will tendto be deflected out of the vertical position and will apply a load tothe double acting plunger unit 15. If the obstruction to the doormovement is suiiicient to overcome the predetermined compressive forceof spring 23 (FIGURE 5) contained within the unit 1S then the trigger 6will be deflected until it disengages from the pawls even though theseare supported in their fully upwards position by the magnetic lines offorce emanating from the coils 21 and 22.

The device 7 therefore not only disconnects the door from its mechanicallinkage in the event of a power failure but proves an additional safetyfeature to meet overload conditions which may occur at the verticaledges of the door leaves themselves or `at the tracks, hangers orguides. This feature will prevent serious injury being caused to aperson using the door and having part of their body or a limb trappedbetween the closing edges of a door leaf or leaves.

It will be seen that, if the trigger is disengaged from the pawls eitherby a forcible restraint of the door leaf or as a result of a powerfailure, then when the restraint is removed or the electrical supplyrestored, at some point during the first sequence of operationsfollowing these events the trigger 6 will re-engage with the two pawls.Depending on the direction of approach, either pawl 17 or pawl 18 willbe deflected downwards yby the trigger 6 until the edge of the triggermeets the undeflected pawl, when the deected pawl will revert to itsoperating attitude and the door gear will be ready for normal ruse.

The sectional view in FIGURE 4 of the door operating mechanism shows howthis can be sufficiently cornpact to be contained within a housing 1which is suficiently compact in form to constitute the lintel or transommember of the door frame, having regard to the modern requirement forsuch members to be slim and compact in appearance.

As FIGURES 5 and 6 show, unit 15 consists of a cylinder 31 having at oneend an eye 32 for attachment to trigger 6 and at the other end la hole33 for pivoting on nut 4. Eye 32 is attached to rod 34 which passesthrough spring seats 35 and 36 has a head 37 behind seat 36. Spring 23acts between seats 35, 36. Thus eye 32 can move in either axialdirection carrying with it one spring seat while the other seat isstationary, thus compressing spring 23 to provide a restoring force.

I claim:

1. Electrically-operated sliding door gear including a driving mechanismfor transmitting a driving force to at least one door leaf, saidmechanism including a power operated coupling device, said couplingdevice comprising driving and driven parts, two pawls carried by one ofthe parts, a predeterminedly spring-loaded trigger member carried by theother of the parts, the pawls having a normal rest position clear of thetrigger member and a second position in which they can be engaged by thetrigger member, and electromagnetic means for holding the pawls in theirsecond position when the dooroperating power supply is on whereby saidpawls become disengaged from the trigger member when door-operatingpower is absent and override the trigger member when resistance tomovement of the driven part exceeds a predetermined amount andsubsequently re-engage the trigger member automatically on furtheroperation of the door gear.

2. The electrically-operated sliding door gear as claimed in claim 1, inwhich the driving mechanism includes a lead screw and a non-rotatablenut threaded on the screw, and said nut constituting the driving part ofthe coupling device.

3. The electrically-operated sliding door gear Aas claimed in claim 1,in which said trigger is pivoted on the driving part and the pawls arepivoted on the driven part of the coupling device.

References Cited FOREIGN PATENTS 12/ 1947 Australia. 12/ 1934 GreatBritain.

